Apparatus for centrifugally casting an article with an internal flange

ABSTRACT

CENTRIFUGALLY CASTING A TUBULAR ARTICLE HAVING AT LEAST ONE INTERNAL FLANGE. A REFRACTORY CORE IS PLACED IN AN ELONGATED TUBULAR MOLD. THE CORE INCLUDES A DAM MEMBER AND A FLANGE CHAMBER. AN INITIAL POUR OF MOLTEN METAL IS INTRODUCED INTO THE MOLD ON ONE SIDE OF THE CORE. THE INITIAL LAYER OF METAL IS COOLED UNTIL A SEAL IS FORMED BETWEEN THE DAM MEMBER AND THE TUBULAR WALL. A SECOND POUR OF MOLTEN METAL IS MADE ON THE OTHER SIDE OF THE DAM MEMBER. THIS SECOND LAYER OF MOLTEN MATERIAL FILLS THE FLANGE CHAMBER BY PASSING THROUGH A SERIES OF PASSAGEWAYS LEADING INTO SUCH FLANGE CHAMBER. SUBSEQUENTLY, THE CASTING IS COOLED AND REMOVED FROM THE MOLD.

United States Patent [72] Inventor Walter H. Bade Huron, Ohio 21 Appl. No. 761,268 [22] Filed Sept. 20, 1968 [45] Patented June 28, DH [73] Assignee Saudusky Foundry & Machine Company Sandusky,-0hio [54] APPARATUS FOR CENTRII-UGALLY CASTING A ARTICLE WITH AN INTERNAL FLANGE 3 Claims, 7 Drawing Figs.

[52] US. Cl 164/302, 164/1 14 [51] Int. Cl ..B22d 13/10, 8220 9/08 [50] Field ot'Search 164/114, 298-302, 91, 288

[56] References Cited UNITED STATES PATENTS 3,263,285 8/1966 Rojecki 164/114 $293,708 12/1966 Fruitinan 164/114 3,478,811 11/1969 Notbohm 164/298X FOREIGN PATENTS 785,319 10/1957 Great Britain 164/114 Primary Examinerl. Spencer Overholser Assistant Examiner-R. Spencer Annear Attorney-Owen and Owen ABSTRACT: Centrifugally casting a tubular article having at least one internal flange. A refractory core is placed in an elongated tubular mold. The core includes a dam member and a flange chamber. An initial pour of molten metal is introduced into the mold on one side of the core. The initial layer of metal is cooled until a seal is formed between the dam member and the tubular wall. A second pour of molten metal is made on the other side of the dam member. This second layer of molten material fills the flange chamber by passing through a series of passageways leading into such flange chamber. Subsequently, the casting is cooled and removed from the mold.

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APPARATUS FOR CENTRIFUGALLY CASTING AN ARTICLE WITH AN INTERNAL FLANGE BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for centrifugally casting a large hollow roll shell having at least one interior flange. In a centrifugal casting process the mold, either sand-lined or permanent, is rotated to effect a predetermined centrifugal force upon a poured molten material. As the molten material is introduced into the mold, it is urged outwardly upon the interior surface of the mold and a cylindrical article having a uniform and continuous inner surface is formed. Because the centrifugal force urges the molten metal outwardly, it is relatively simple to form a centrifugal casting with an exterior flange. However, an inherent difficulty lies in the production of a centrifugal casting with an interior flange because of the tendency of the molten material under centrifugal force to seek a uniform level along the interior wall of the casting.

The prior art has made attempts at centrifugally casting an article having an interior flange. U.S. Pat. No. 3,263,285 discloses introducing a pressurized fluid into the center of the tu bular mold to force the molten material into outwardly positioned flange chambers. U.S. Pat. No. 3,293,708 discloses the introduction of a waste molten material, such as slag, salt or the like, into the center of the mold. At the same time, the casting molten material is introduced into outer flange chambers. The waste material prevents the passage of the primary molten metal into the central area of the tubular mold. British Patent No. 785,319 (Oct. 23, I957) discloses the use of a metal flange annulus which is fused into the casting material and becomes an integral part of the casting.

Another problem in the art is the production of large sized cast rolls with internal flanges which are adapted for use in heavy machinery, for example in paper making machinery. The sheer size of these cast rolls create problems not present in centrifugally casting small rolls. The problems of excessive contractions; excessive internal strains; metallurgical differences in the casting cross section; and the difficulties involved in attempting to uniformly cool massive castings are but a few of the problems which make the centrifugal casting of large rolls with internal flanges particularly difficult.

SUMMARY OF THE INVENTION The present invention solves the major problems of the prior art by providing a method and apparatus for centrifugally casting articles having at least one internal flange. The present invention is readily useable in the production of rela tively massive castings.

The centrifugal casting assembly, according to the invention, includes an elongated tubular mold having a longitudinal axis and opposed end plates. At least one refractory core is positioned at a predetermined location within the tubular mold. The core includes an annular dam member positioned perpendicular to the longitudinal axis of the mold. A cylindrical neck member is connected to the dam. member and a face member is connected to the opposite end of the neck member. The dam member, the face member, and the neck member define a flange chamber. The face member has a plurality of passageways which lead into the flange chamber.

Molten metal is introduced into the rotating mold on a first side of the core. The initial layer of molten metal is cooled until a seal is formed between the dam member of the core and the tubular casting'wall. Another layer of molten metal is then introduced into the mold on the opposite side of the dam member. A portion of this second layer passes through the passageways in the face member and fills the flange chamber.

Subsequently, the cast article is cooled. During the cooling cycle the mold is rotated. The cast article is then pulled from the mold and the core and waste portion of the cast material removed.

It is the primary object of the present invention to provide an improved method and apparatus for centrifugally casting a tubular article having at least one internal flange.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a core, constructed according to the present invention, with parts broken away;

FIG. 2 is a longitudinal cross-sectional view of the core shown in FIG. 1;

FIG. 3 is an end view taken along the line 3-3 of FIG. 2 and showing a portion of the core broken away;

FIG. 4 is a fragmentary, diagrammatic, and cross-sectional view of a centrifugal casting assembly, constructed according to the present invention, illustrating the pouring of an initial layer of molten metal;

FIG. 5 is a view similar to FIG. 4 showing the pouring of another layer of molten metal;

FIG. 6 is an elevational view, partially in cross section, showing the casting article after it has been removed from the mold and prior to the removal of the waste casting metal; and

FIG. 7 is a fragmentary, elevational view, partially in cross section of the finished casting article.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 4 and 5, a centrifugal casting assembly, according to the present invention, is generally indicated by the reference number 10. The assembly 10 includes a metallic tubular case 11 having a sand lining 12. In the present embodiment the case 11 and the sand lining 12 form an elongated tubular mold which has a longitudinal axis of rotation indicated by the reference number 13. However, molds other than sandlined molds may be used, for example, a permanent mold with a refractory mold wash material placed on its interior diameter.

The centrifugal casting assembly 10 also includes removable end plate assemblies 14 mounted at opposed ends of the tubular mold. The end plates 14 have circular openings 15 for the introduction of pouring spouts as indicated by the dashed lines in FIGS. 4 and 5.

Referring in particular to FIGS. 1, 2 and 3, a core 18 is positioned within the tubular mold. In the present embodiment, cores 18 are positioned adjacent the end plates 14 at opposed ends of the mold. This results in the formation of a cast article having internal flanges adjacent both of its outermost ends. However, the positioning and number of the cores and the resultant interior flanges varies and is determined by the ultimate use of the finished cast article.

The core 18 is preferably constructed of high density refractory material and is preferably provided with reinforcing members 19. The refractory material is castable and able to withstand temperatures in the 2000 F. to 3000 F. range. The core 18 includes a dam member 20 which is in the shape of an annulus. The dam member 20 has a central opening 21 and an outer periphery 22. The periphery 22 is concentric with the mold after the core 18 is placed in position adjacent the sand lining 12. When the core 18 is positioned within the centrifugal casting assembly 10, the outer periphery 22 of the dam member 20 is spaced a predetermined distance from the sand lining 12. The predetermined distance is slightly less than the wall thickness of the article to be cast. When the first layer of molten metal is poured a seal is formed between the dam member 20 and the first layer of metal, as explained below.

The core 18 also includes a cylindrical neck member 23 having a central passageway 24. The neck member 23 is concentrically connected to the dam member 20 and the central passageway 24 is in communication with the central opening 21. Preferably, the neck member 23 defines a plurality of vents 25.

An annular face member 26 having a center hole 27 is connected to the neck member 23 in opposed relationship to the dam member 20. The face member 26, the neck member 23, and the dam member 20 define a flange chamber generally indicated by the reference number 29. The center hole 27 of the face member 26 is in communication with the central passageway 24 of the neck member 23 and the central opening 21 of the dam member 20. The vents 25 in the neck member 23 permit the passage of gases between the flange chamber 29 and the central passageway 24. The face member 26 is provided with a plurality of circumferentially spaced feed passageways or openings 30 which extend through the face member 26 into the flange chamber 29.

Preferably, the core also includes a cylindrical wall member 31 which is coaxially mounted on the face member 26 in opposed relationship to the neck member 23. The wall member 31 includes a plurality of spaced openings 33 which serve as retaining means for holding the core 18 in a predetermined position within the mold during the casting operation.

Referring to FIGS. 4 and 5, the core 18 is placed in the centrifugal casting assembly at a predetermined location along the longitudinal axis 13. In the present embodiment, a cylindrical wall member 31 abuts the inner side of each end plate assembly 14. Therefore, the length of the cylindrical wall member 31 positions the flange chamber 29 in this embodiment. Retaining pins 34 extend through the retaining openings 33 in the wall member 31 into the sand lining 12. The retaining openings 33 and the pins 34 serve as retaining means to prevent relative longitudinal movement between the mold case 11 and the core 18, prior to and during the pouring of the first layer of molten metal.

Referring to FIG. 7, a finished cast article 36 includes a tubular wall 37 and internal flanges 38. In the present method of casting the article 36, after the core 18 is positioned within the centrifugal casting assembly 10, the entire centrifugal casting assembly 10 is rotated about its longitudinal axis 13. Referring to FIG. 4, a pouring spout indicated by the reference number 39a extends through the opening in the end plate assembly 14 and through a pouring passageway defined by the center hole 27, the central passageway 24, and the central opening 21. It is very important that no obstructions or supporting members be located along the longitudinal centerline 13 which would strike or bump the pouring spout 39 as it is placing the molten metal within the centrifugal casting assembly 10. The pouring of tons of molten metal at temperatures in excess of 2000 F. requires that any possible interference with either the pouring spout 39 or the molten metal itself be eliminated. An initial layer of molten metal is introduced into the mold through the pouring spout 39a as indicated by the dashed lines in FIG. 4. This layer of molten metal forms the outer shell or wall v37 of the cast article. The mold is rotated and the initial layer of molten metal is cooled until a seal is,

formed between the outer periphery 22 of the dam member and the casting wall 37.

Referring to FIG. 5, a pouring spout is then moved to the position indicated by the reference number 39b. Another layer of molten metal is introduced through the pouring spout 39 into the area between the core face member 26 and the end plate assembly 14. A portion of the second layer of molten metal passes through the feed passageways or openings into the flange chamber 29. The pour is continued until the flange chamber 29 is filled with molten metal. The internal flange 38 is formed within the flange chamber 29. Any trapped gases are expelled through the vents 25 defined in the neck member 23 (see FIG. 2). A metallurgical bond is created between the initial layer of molten material and the second layer of molten material along a cylindrical surface of revolution indicated by the reference number 40 in FIG. 5. During pouring of the second layer, the seal between the outer periphery 22 of the dam member 20 and the wall 37 of the casting prevents introduction of the second layer of molten metal into the central area of the casting assembly 10 where it would, of course, seek a uniform depth throughout the length of the mold.

After introduction of the second layer of molten metal into the flange chamber 29, the centrifugal casting assembly 10 continues to rotate at least during the initial cooling of the cast article 36.

After cooling to a predetermined temperature, the casting 36 is removed from the casting assembly 10. The core 18 is destroyed and the casting 36 appears as shown in FIG. 6. As it is removed from the mold, the casting 36 includes waste metal 41, which is the molten metal received in the area between the face member 26, the wall member 31, and the end plate assembly 14. The waste metal 41 also includes the metal which solidified within the feed passageways or openings 30. The waste metal 41 is severed along the line A-A as shown in FIG. 6 and the finished cast article 36 is shown in FIG. 7. The finished casting 36 is suitable for use in, for example, paper machinery. Often, bores are provided in the internal flanges 38 for use in the mounting of the finished rolls within the paper making machinery.

lclaim:

1. A centrifugal casting assembly for the manufacture of cylindrical castings having at least one internal flange comprising, in combination, an elongated tubular mold having a longitudinal axis and opposed ends, end plate assemblies removably connected to such opposed ends for the retention of molten metal to be cast, and at least one integral core constructed ofa high density, reinforced, refractory material positioned at a predetermined location in said tubular mold, said core including an annular dam member, a cylindrical neck member connected to said dam member, and annular face member connected to said neck member in opposed relation to said dam member, and a cylindrical wall member coaxially and concentrically mounted on said face member in opposed relationship to said neck member, said wall member being contiguous to the inside of the mold, said dam member, said neck member and said face member defining a continuous pouring passageway therethrough, said face member, said neck member and said dam member also defining a flange chamber adjacent said tubular mold, said face member having a plurality of openings leading into such flange chamber, said openings being circumferentially spaced and located a predetermined radial distance from such longitudinal axis.

2. A centrifugal casting assembly according to claim 1, and means for retaining said core in a predetermined position within said mold.

3. A centrifugal casting assembly according to claim 2, wherein said annular dam member has an outer periphery concentrically spaced a predetermined distance from the inside of the mold, said predetermined distance being slightly less than the wall thickness of the desired cylindrical casting, whereby a seal is formed between the dam and the casting during an initial pour of casting material. 

